Japanese Patent No. 4385406 (JP 4385406) discloses a linear motor body including a mover and a stator, the mover including a direct drive shaft capable of reciprocating in an axial direction thereof and a permanent magnet array mounted to the direct drive shaft, the stator having a plurality of excitation windings each formed of a winding conductor wound in a coil such that the mover reciprocates in an inner space defined inside the excitation windings. Aback yoke is disposed outside the stator of the linear motor body to partly form a magnetic circuit of the linear motor body. The back yoke is constituted from a pipe made of magnetic material. In this example, there are a plurality of linear motor bodies that are supported, being sandwiched between a block frame and a cover.
The manufacturing process of such conventional linear motor is complicated since the back yoke formed of a pipe must be mounted onto linear motor bodies. In addition, the back yoke is large in size and heavy in weight. Consequently, the linear motor is inevitably large in volume and heavy in weight.